This disclosure is related to the field of passive seismic monitoring of hydraulic fracturing of subsurface formations. More specifically, the disclosure is related to determining aggregate properties of a fracture treatment to assist a well operator in planning further fracture treatments and/or locations of additional wellbores within a subsurface formation.
Hydraulic fracturing of subsurface formations is known in the art for increasing the effective wellbore radius in a subsurface formation. Such effect may provide the benefits of providing a permeable path through portions of the formation proximate a well drilled therethrough (called “skin damage”) so as to increase the productivity of such wells. Hydraulic fracturing is also known to be used to create permeable interconnections between naturally occurring fractures in subsurface formations so that a well traversing such formations may cumulatively produce enough hydrocarbons so as to be economically viable. Most hydraulic fracturing techniques known in the art include pumping a fluid with suspended solid particles (proppant) into a wellbore that is in hydraulic communication with a formation of interest. Pressure of the carrying fluid is set so as to exceed the fracture pressure of the formation of interest. Once the proppant is emplaced where desired in the formation, the carrying fluid may change its rheological properties, e.g., a gel type fracturing fluid may revert to the properties of plain water, and thus be more amenable to removal from the formation (“clean up”).
It is known in the art to use passive seismic sensing to determine the hypocenters (time and position of origin) of fracture events created by hydraulic fracturing. Such determination may be performed during a fracturing procedure to determine spatial distribution of the hydraulic fractures thus created. One such technique is described in U.S. Pat. No. 7,663,970 issued to Duncan et al.